Pyrocumulonimbus cloud in Bolivia

August 18th, 2019 |

GOES-16

GOES-16 “Red” Visible (0.64 µm, top), Shortwave Infrared (3.9 µm, middle) and “Clean” Infrared Window (10.35 µm, bottom) images [click to play animation | MP4]

GOES-16 (GOES-East) “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm) and “Clean” Infrared Window (10.35 µm) images (above) showed the formation of a pyrocumulonimbus (pyroCb) cloud over far southeastern Bolivia on 18 August 2019. The small anvil cloud briefly surpassed the -40ºC pyroCb threshold from 1800-1820 UTC, attaining a minimum cloud-top infrared brightness temperature of -45.2ºC along the Bolivia/Paraguay border at 1800 UTC. This pyroCb formed over the hottest southern portion of an elongated fire line, as seen in the Shortwave Infrared imagery.

A 1.5-day animation of GOES-16 Shortwave Infrared images (from 12 UTC on 17 August to 2350 UTC on 18 August) revealed the rapid southeastward run of the fire to the Bolivia/Paraguay border on 17 August, followed by the eastward expansion of the fire line on 18 August (below).

GOES-16 Shortwave Infrared (3.9 µm) images [click to play animation | MP4]

GOES-16 Shortwave Infrared (3.9 µm) images [click to play animation | MP4]

A toggle between Suomi NPP VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) images as viewed using RealEarth (below) showed the large and dense smoke plume streaming southeastward, with the small pyroCb along the Bolivia/Paraguay border at 1745 UTC — the brighter white tops of the pyrocumulus and pyrocumulonimbus clouds reached higher altitudes than the tan-colored smoke plume. The coldest cloud-top infrared brightness temperature was about -55ºC (orange enhancement), which corresponded to an altitude around 9 km according to rawinsonde data from Corumbá, Bolivia.

Suomi NPP VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) images [click to enlarge]

Suomi NPP VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) images [click to enlarge]


Strong northerly to northwesterly surface winds were blowing across the region, in advance of an approaching cold front (surface analyses) — at Robore, Bolivia (located just north-northwest of the fires), winds were gusting to 25-28 knots during much of the day (below).

Time series of surface report data from Robore, Bolivia [click to enlarge]

Time series of surface report data from Robore, Bolivia [click to enlarge]

This is likely the second confirmed case of a South American pyroCb (the first being on 29 January 2018) — in addition, it’s the second pyroCb documented in the tropics and the first pyroCb documented during a winter season. Thanks to Mike Fromm (NRL) for bringing this case to our attention!

Largest hailstone on record for the state of Colorado

August 13th, 2019 |

GOES-16

GOES-16 “Red” Visible (0.64 µm, left) and “Clean” Infrared Window (10.35 µm, right) images, with plots of SPC Storm Reports [click to play animation | MP4]

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images (above) displayed the increasing coverage of thunderstorms along the Colorado/Kansas border on 13 August 2019, These thunderstorms produced a few tornadoes and large hail — including hail of 5.00 inches in diameter at 2135 UTC near Bethune in extreme eastern Colorado (SPC storm reports).

 

A toggle between NOAA-20 VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images (below) showed the storms at 2022 UTC — just over an hour before the 5.00-inch hail report at 2135 UTC. Note that the NOAA-20 images are incorrectly labelled as Suomi NPP.

NOAA-20 Visible (0.64 µm) and Infrared Window (11.45 µm) images, with NUCAPS sounding locations and surface reports [click to enlarge]

NOAA-20 VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images, with NUCAPS sounding locations and surface reports [click to enlarge]

The NOAA-20 NUCAPS profile for the green dot in far western Kansas (below) showed that the airmass in advance of the approaching thunderstorms was very unstable, with a Most Unstable parcel Convective Available Potential Energy (MU CAPE) value of 2737 J/kg and a Lifted Index (LI) value of -10ºC (with no Convective Inhibition CINH).

NOAA-20 NUCAPS profile in far western Kansas [click to enlarge

NOAA-20 NUCAPS profile in far western Kansas [click to enlarge]

In contrast, the NUCAPS profile for the green dot in eastern Colorado (below) revealed an airmass that was less unstable in the wake of the departing thunderstorms.

NOAA-20 NUCAPS profile in eastern Colorado [click to enlarge]

NOAA-20 NUCAPS profile in eastern Colorado [click to enlarge]

===== 14 August Update =====

NWS Goodland Public Information Statement.

 

 

Hurricane Erick in the East Pacific Ocean

July 30th, 2019 |

GOES-17

GOES-17 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

1-minute Mesoscale Domain Sector GOES-17 (GOES-West) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images (above) showed the well-defined eye of Hurricane Erick on 30 July 2019. Mesovortices could be seen within the eye on the visible imagery, along with periodic convective bursts within the surrounding eyewall region — and cloud-top infrared brightness temperatures as cold as -84ºC were associated with these convective bursts.

Prior to sunrise Erick experienced a period of rapid intensification, as seen in a Advanced Dvorak Technique plot from the CIMSS Tropical Cyclones site (below). Erick was classified as a Category 4 hurricane as of the 18 UTC advisory.

Advanced Dvorak Technique (ADT) plot for Hurricane Erick [click to enlarge]

Advanced Dvorak Technique (ADT) plot for Hurricane Erick [click to enlarge]

Around the time that the period of rapid intensification was beginning, a NOAA-20 VIIRS Infrared Window (11.45 µm) image viewed using RealEarth (below) revealed a distinct eye around 11 UTC.

NOAA-20 VIIRS Infrared Window (11.45 µm) image [click to enlarge]

NOAA-20 VIIRS Infrared Window (11.45 µm) image [click to enlarge]

NUCAPS Profiles are back in AWIPS

July 2nd, 2019 |

1200 UTC Soundings from KGYX (Grey Maine) on 2 July 2019 and 1600 UTC NUCAPS sounding from nearby, showing changes in the thermodynamics (Click to enlarge)

Back in late March 2019, the Cross-track Infrared Sounder (CrIS) suffered an anomaly such that the mid-wave portion of the electromagnetic spectrum (a part that includes channels sensitive to water vapor) was not scanned properly. Thus, NUCAPS soundings created from Suomi-NPP were lost (link). Today, NUCAPS soundings created using NOAA-20 (which has the same instruments as Suomi-NPP) began flowing into AWIPS. Data from shortly after 1500 UTC were the first to appear.

NUCAPS Soundings over the northeastern United States at 1629 UTC on 2 July 2019 (Click to enlarge)

NUCAPS profiles from NOAA-20 are processed somewhat differently than those from Suomi-NPP as far as latency: NOAA-20 NUCAPS profiles show up more quickly — typically within an hour of the observations time — in AWIPS than NPP NUCAPS profiles did. This is important because the thermodynamic information in these mid-afternoon observations is important in judging destabilization relative to morning soundings.

When Suomi NPP was launched, two independent sets of electronics were present on CrIS; the ‘A’-side set of electronics were used until March; the ‘B’-side electronics have been used since June, and mid-wave observations from Suomi-NPP’s CrIS are now available at this site. However, NUCAPS soundings are not yet being created from Suomi-NPP because the A-side and B-side electronics have different statistical behavior that must be accounted for in the Regression used to start the NUCAPS processing.